This description relates to loop inductance in electrical circuits, and more particularly, to systems and methods for reducing loop inductance in electrical circuits.
Known electrical circuits often include sections in which a current passes from a first component to a second component and returns to the first component. The paths between the first and second component form a current loop. FIG. 1 is a diagram of a portion of an electrical circuit 10 including a current loop 15. The electrical circuit 10 is part of a power converter, e.g., an inverter or a multi-level converter. Current loop 15 includes a source conductor 20 and a return conductor 25. Circuit 10 includes phase leg 30 of a power converter coupled to a direct current DC link capacitor 35 by source conductor 20 and return conductor 25. Current loop 15 defines a loop area 40 within current loop 15. During operation of circuit 10, current passes around current loop 15, for example clockwise around loop 15. Current loop 15 has a parasitic inductance, sometimes referred to as a loop inductance, that depends on the shape and size of current loop 15. The inductance of current loop 15 is proportional to the area of loop area 40. Unintended loop inductance may cause malfunctioning in electrical circuits. In general circuit designers identify sources of loop inductance, calculate the inductance, and factor the loop inductance into the circuit design to permit the circuit to operate as intended. Loop inductance may result in relatively large voltage overshoot and ringing in switching circuits, such as circuit 10.
Some known systems attempt to reduce the inductance of current loops by placing source and return conductors closer together, thereby reducing the area of the current loop. In high voltage circuits, however, source and return conductors located close together may be susceptible to arcing and insulation breakdown. Other known systems attempt to reduce loop inductance by using wide conductive plates separated by insulation, rather than wires, for the source and return conductors. Electrical circuits using wide plates instead of wires can be more expensive, more difficult to construct, and larger than wire based systems. Another known method to reduce loop inductance is to use a twisted pair of wires for the source and return conductors, but this can be difficult to construct for high voltage and high current use.